The chemoprevention of colon cancer has been hampered by either weak agents or significant side effects. It was recently shown that the combination of sulindac with difluoromethylornithine (DFMO) prevents nearly 70% of colon cancer, assessed as colon polyp recurrence. Sulindac, however, has frequent and significant side-effects that make its long-term application to cancer prevention problematic. Our phase I STTR assessed the potential role of our sulindac-like compound MDC-1231, also known as phosphosulindac (PS), in colon cancer prevention. PS has increased potency and safety compared to sulindac and acts synergistically with DFMO to prevent colon cancer with an efficacy of 91%. Our goal is to replace sulindac with PS in the successful combination with DFMO in order to develop a superior approach to colon cancer prevention. We have accomplished all the goals of the phase I grant. The goal of the present phase II application is to complete the preclinical development of PS and submit an FDA IND application. We propose five specific aims, some of them will be pursued in parallel and influence each other. Specific Aim #1: Complete the studies on the metabolism; perform PK/PD and biodistribution of the optimized oral formulation of PS. Specific Aim #2: Scale up the synthesis of PS under GMP conditions. Specific Aim #3: Develop an oral formulation of PS and determine its stability. Specific Aim #4: Perform toxicity studies of PS; they include animal toxicity and genotoxicity studies. Specific Aim #5: Prepare an IND protocol and package for FDA submission. The proposed work, if successful, will contribute greatly towards a realistic strategy for human colon cancer chemoprevention.